2.3. DNA extraction To separate the mouthwash, the tube was centrifuged during 10 min at 10750x g. The supernatant was poured out and the cellular pellet washed with 1 ml of PBS, resuspended in the vortex for 30 s, and transferred to a new 2 ml tube. It was then centrifuged for 5 min at 2000x g, the supernatant poured out, and the pellet washed with 1.5 ml of PBS and resuspended in the vortex for 30 s. To this solution was added a 1 ml solution of lysis of nucleated cells (Wizard® Genomic DNA Purification Kit) before being shaken for 20 s, followed by incubation at 37 °C for 10 min. After adding 300 µl of protein precipitator solution (Wizard® Genomic DNA Purification Kit), the mixture was placed on ice for 5 min and then centrifuged at 15000x g for 3 min. The supernatant was put in a 1.5 ml tube containing 600 µL cold Isopropanol and homogenized gently, then centrifuged at 15000x for 3 min. The supernatant was poured out and 600 µL of 70% ethanol were added to a fresh preparation, which was centrifuged at 15000x g for 3 min. The supernatant was poured out and the tube was completely dried at room temperature. Finally, 100 µL rehydration solution (Wizard® Genomic DNA Purification Kit) was added and the mixture was incubated at 64 °C for 1 h before storing the samples at -20 °C to await further processing.